Mineral oil distillation



J. E@ scHuLzE MINERAL OILDISTILLATIQN Filed Aug. 24,

1925 3 Sheets-Sheet 1 Jk-n E.

Oct, 15, 1935- J.- E. SCHULZE MINERAL OIL DISTILLATION 2 t e e h s t e e h s 3 Filed Aug. 24, 1925 5, 1935- J. E. SCHULZE MINERAL OIL DISTILLATION Filed Aug. 24, 1925 5 Sheets-Sheet 3 v 8% Wm Wm.

Patented Oct. 15, 1935 UNITED STATES:

PATENT OFFICE MINERAL OIL DISTILLATION John E. Schulze, Hammond, 1116., assignor, by

mesne assignments, to Red River Refining Company, Chicago, 111., a corporation of Delaware Application August 24, 1925, Serial No. 52,118-

26 Claims.

vacuum, the invention is of greatest present utility in that field which will therefore be more particularly referred to hereinafter in explaining the principles upon which the broad invention rests.

In a prior patent, No. 1,448,709, granted March 13, 1923, this applicant has disclosed and claimed a high vacuum distillation process for the manufacture of useful products, notably lubricating oils, from petroleum oils and residues; and the present invention, although broad in scope as above indicated, is concerned more par ticularly with the manufacture of high grade lubricating oils by methods involving broadly the principles and conditions of operation disclosed in said prior patent.

The patented process aforesaid makes use of distillation pressures which do not exceed millimeters mercury absolute'as a maximum and which are most desirably even much lower, commonly 5 millimeters or less. Said process gives excellent resultsdn practice and at the present time is employed commercially on a large scale for the manufacture of high grade lubricating oils. Nevertheless it has been found that with certain types of crudes or residua, especially those high in combined sulfur, nitrogen, organic acids, or complexes including some or all of such constituents, difficulty is sometimes experienced in obtaining by the patented process lubricating oil fractions that are perfectly sweet as to odor and taste and that do not darken in color or assume an undesirable cast after prolonged exa posure to light or standing in storage for a considerable time. This instability and other unsatisfactory characteristics of lubricating oil distillates obtained from such starting materials are due to the presence in said distillates of organic acids or compounds of sulfur or nitrogen, or complexes of these, which are tenaciously held by the lubricating distillates notwithstanding the fact that such contaminating impurities are generally of substantially lower boiling point than said distillates.

aspects to distillation of lubricating oils under' Among such crude oils above referred to may be mentioned by way of example the following:

- Gravity 17.3" B. smackover crude -{s 1f about 3% Nevada County Gravity 14 B. (Arkansas) crude "{Sulfur about 3% Cacalilao {Gravity 12 B. (Mexico) crude Sulfur about 4 to 5%.

California and Mexican crudes generally, most 16 of which are high in sulfur and in organic acids especially.

The foregoing are merely typical of starting materials well adapted for manufacture of high grade lubricating oils by the process of the presl5 ent invention. Heretofore it has been impossible to produce marketable lubricating .oilsfrom such starting materials.

Principal objects of the inventionare to provide a method or process wherein the diificulties 20 heretofore encountered in utilizing this class of starting materials are overcome and production of valuable and thoroughly satisfactory high grade distillates is made possible, especially lubricating oil distillates, from low grade crudes and 25 residua of the type above discussed; also to provide apparatus for carrying out such method. Other objects are in general to make it possible to obtain from such starting materials sweet and stable mineral oil distillates, whether lubricating 30 oils or not, and also irrespective of whether the distillation'be conducted under high vacuum or not. Still further objects and advantages of the invention will become apparent as the description proceeds.

In general, the process of the present invention involves vaporization of the crude petroleum or other mineral oil starting material, or a large part thereof, and fractional condensation of the I resultant vapors in such manner that separation 40 of the desired condensate is effected with minimum exposure thereof to contact with the lighter vapors and gases which carry most of the deleterious compounds it is desired to exclude from said condensate, so that little or no opportunity is afforded for said condensate to absorb and become contaminated vby said compounds. In the best way of practicing. the invention, the desired condensate obtained in the fractional condensa- 50 tion is not allowed to cool materially below the temperature at which it is formed until after there is no further opportunity for contacting with the malodorous vapors and gases before mentioned.

Most desirably, but not necessarily in all cases, the vaporization of the crude oil is accomplished by distillation under high vacuum of the order of magnitude characterizing the process disclosed in said Patent No. 1,448,709 before mentioned. Furthermore, by employing an appropriately arranged apparatus and properly operating the same, it is feasible simultaneously to apply differing degrees of vacuum to the desired liquid condensate on the one hand, and to the uncondensed malodorous vapors and gases on the other, respectively, whereby removal of said vapors and gases from the vicinity of said condensate may be greatly promoted and expedited with advantage.

In processing a given mineral oil starting material in accordance with the invention, it is also highly desirable, where such material is high in impurities such as those hereinabove mentioned, to conduct the distillation in the presence of a small quantity of a neutralizing agent that is alkaline in nature, such as causticsoda, soda ash, lime, or other suitable basic reagent. The employment of such a neutralizing agent may be in connection with an initial distillation of the starting material or in connection with a redistillation pf a crude or raw distillate obtained in an initial run. The conjoint use of such a neutralizing agent and the method of separating malodorous volatile products as uncondensed vapors and gases from the desired condensates, in the manner outlined generally above, gives excel lent results and constitutes an important feature of the invention, as will more fully hereinafter appear.

In order to afford a full understanding of the principles of the invention, a typical practical embodiment thereof will now be described in detail in connection with the accompanying drawings which illustrate an appropriate apparatus installation for carrying out the process. In these drawings 7 Fig. 1 is a side elevation of such installation;

Fig. 2 is a plan of same; and

Fig. 3 is a view in side elevation of an installation similar to that shown in Figs. 1 and 2 but modified to permit employment of steam in the distillation. In all the views, parts are shown broken away and in section. 1

Referring to the drawings, l 0 represents a horizontal cylindrical still supported above a heating furnace indicated generally at H which may be constructed and fired in any suitable manner to 55., heat the still indirectly rather than by direct contact of flame with the still bottom. In the present instance,the still Ill is especially constructed for operation under extremely high vacuum (i. e. extremely low absolute pressure) of an order of magnitude corresponding to 25 millimeters of mercury (or less) absolute pressure. To this end the still is interiorly braced as, for example, in the manner illustrated in my prior Patent No. 1,448,709, dated March 13, 1923. In order to provide vapor offtake means of ample cross-sectional area, the still is equipped with a plurality of vapor offtakes I2, in this instance ten in number, of uniform diameter, leaving the still at uniformly spaced points along the length thereof. The vertical portion l2- of each of the vapor offtakes I2 is relatively very shnrtin order to minimize refluxing of distillate to the still. To the same end. the remainder of each of the vapor oiftakes is inclined downwardly from the vertical portion l2 toward 'the cooling coil I 3 into which each ofitake l2 leads. These c 01- 'discharge into a large-diameter collecting header ing coils I3 are submerged in cooling water contained in a box or tank l4. Said cooling coils, one of which is providedfor each oiftake l2,

At I6 is a riser, one for each offtake l2, the risers Hi all entering a horizontal header l1. From the header l1 two sets of vapor lines l8 and I9 extend upwardly a considerable distance above the header l1 and then bend downwardly 10 to connect with cooling coils and 2|, respectively, disposed in cooling tank M. In the pres-, ent instance, there are three vapor lines l8 in one set and two vapor lines IS) in the other set. The coils 20 and 2 I, of which there are two in this case and which are of larger diameter than the lines l8 and I9, discharge into a collecting header 22 of still larger diameter.

The described arrangement of the vapor pipes 18 and IS in sets discharging, respectively, into separate cooling coils 20 and 2| is in harmony with the general purpose of ensuring ample crosssectional area at all points in the piping system leading from the still. This general purpose may be accomplished in various ways, of course, but25 the arrangement here shown byway of example is effective and satisfactory in practice.

The piping system just described, beginning with risers l6 and extending to header 22 constitute parts of what may be conveniently termed 80 the header distillate" line or deodorizer system, further reference to which will be made hereinafter.

Provision is made for guarding against substantial condensation of vapors at the point 85 where they leave the still and for a short distance therefrom. This is for the double purpose of avoiding refluxing to the still and also of minimizing opportunity for contact of the distillation vapors with liquid condensate formed 0 therefrom. In other words, the object is to get the distillation vapors out of and at least a short distance away from the still before material condensation occurs, and then to effect condensation of the desired liquid products at a. point where no refluxing of condensate to the still takes place, and under conditions such that the condensate and residual uncondensed vapors and gases are rapidly separated from each other so that absorption or solution of such vapors and gases by the condensate is practically prevented.

This object may be attained in various specific ways, but the arrangement here illustrated is a typical practical way of effectively accomplishing the result desired. In the installation here shown, the upper part of the still is covered with heavy heat insulation or lagging 23. Furthermore, each of the vapor offtakes I2, is similarly insulated not only over portion l2, but also over its downwardly inclined portion down to the point where the riser l6 branches off. Thus there is substantially no condensation in any of the offtakes l2 until that point is reached. In the present instance, the riser I6 is also shown insulated and the header I1 may also be insulated. But the advisability in any given instance of insulating said risers and header is determined largely by the prevailing atmospheric temperature. Similarly the vapor lines l8, l9, may or may not be insulated from where they leave header I! up to the point where they bend downward again, but in the present example they are uncovered and therefore air-cooled. The extent to which these parts, l6l9, of the piping system are insulated may of course be adjusted as rerequire.

ing tanks. 35

quired by seasonal temperature conditions. By

such adjustment the vapors and gases in the ascending lines are on the one hand cooled sufficiently to cause nearly all vapors of desired liquid products to condense, the proportion of such vapors escaping condensation and passing over through the deodorizer system being thus minimized; while on the other hand the cooling in said ascending lines is not carried so far that the deleterious vaporous or gaseous impurities are condensed or their absorption by the useful condensate favored.

The remainder of each offtake !2, beyond the junction of riser l6 therewith, is freely exposed to air-cooling, because in this part of the system collects the desired liquid condensate and proper cooling thereof is advantageous.

Returning now to the header !5, liquid collectng in this header is discharged through rundown line 24 to one of the run-down or receiving tanks indicated at 25, 26, 2'! and 28, there being four such receiving tanks in the battery here illustrated although of course the number may be greater or less as practical operating'conditions Said receiving tanks are connected, respectively, by valved branches 25 26 2'!"- and 28, with the aforesaid line 24. A look-box 29 is placed in a vertical portion of said line.

The header 22 into which the header-distillate lines !8 and I9 discharge is connected by line 30 with header-distillate receiving tank 3| which, for reasons that will appear hereinafter, may be relatively small as compared to the main receiv- A look-box 32 is provided in a vertical portion of line 30, and it is also convenient to provide a sampling device 33 which is connected by valved pipe 34 with line 30, and is also provided with a valved bleeder inlet 35 and a valved draw-off pipe 36.

The entire distilling systemis maintained under the desired degree or degrees 01 vacuum by means of a vacuum pump equipment indicated conventionally at 31, this equipment being either a single vacuum pump of suitable size or a double or triple stage pumping equipment, as may be found most desirable in any given case. The intake of the vacuum pump system has a valved connection 38 to the main vacuum line 39-40 in which header-distillate receiving tank 3| is placed. The four main receiving tanks are connected to said line 39 by valved pipes 4!, 42, 43 and 44, for a purpose that will appear hereinafter. Said pipes extend somewhat above vacuum line 39, as indicated at 45, before entering the same, thus providing against accidental entry from said vacuum line into any of the main receiving tanks, when the valves may be open, of liquid impurities that may collect in said vacuum line.

All seams and joints throughout the apparatus system are made absolutely tight, most desirably by arc-welding, thus making it possible to operate at extremely low absolute pressures and to maintain non-oxidizing conditions during the distillation. Mercury manometers for obfirving the prevailing absolute pressure are provided at different points in the system as indicated, for example at lil for the still, at 25, 26 21 28 for the main receivers, and at 3 for the header-distillate receiver 3!.

In order to illustrate further the principles of the invention, a detailed description will now be given ofone practical procedure that may be used in the manufacture of lubricating oils'in accordance with the new process from Nevada County (Arkansas) crude, employing the above described apparatus system in conducting the distillation. A typical Nevada County crude has a gravity of about 14 Baum as a rule, and ordinarily contains 3% of sulfur or thereabouts. contains practically no gasoline, naphtha or kerosene, the first runnings being gas oil of around 29 Baum gravity. If the crude contains more than one-half of one per cent moisture, as it sometimes does, it should it) first be dehydrated to reduce the moisture content to that proportion or less. This dehydration may be accomplished in various ways known in the art and therefore the operation need not be described here. The crude, sufiiciently free from moisture, is charged into the still Ill up to about 80% of the cubic capacity thereof 'and the still is gradually heated up to within 10 F. or so of the temperature at which the crude has been found by preliminary test to boil initially under 5 mm. mercury absolute pressure. This temperature is usually about 350 F. with the usual run of Nevada County crude. This temperature having been attained, the distilling system is then placed under vacuum by operation of the vacuum pump system indicated at 3'! which, as already explained, may comprise as many single or multiple stage dry vacuum pumps as are found desirable to use in practice. This vacuum is applied to the still, main receivers and other parts of the system through the line 39 and, by way of headerdistillate receiver 3!, through'the header-distillate or deodorizer lines !8, lil. At the outset, the valves connecting the main receiving tanks with run-down line 24, that is, valves 25!, 26!, 21!, and 28!, are all open. So also are valves 30! and 40!. Valve 44! in pipe 44, and also valves 4!!, 42! and 43!, are closed. When the absolute pressure in the still has been reduced to about. 10 mm. absolute, as measured by the manometer 40 lil the initial distillate of gas oil'begins to come over. At this stage, valves 23!, 21!, and 28! may be closed, if desired, assuming that the gas oil is to be collected in receiver 25. By reference to the indicating manometers, it "will be found that 45 the pressure in the still I!) and the header-dis tillate receiving tank 3! is substantially the same, while the pressure in the receiving tank 25 is slightly higher. In practice this difference in pressure should usually amount to some four or five millimeters during the first part of the gas oil out in order that a relatively large quantity of hot oil vapors may be immediately pulled over into the deodorizer system to warm the latter up promptly and get it to functioning properly. 65 Later on, the pressure difference becomes less until by the end of the gas oil out it may have decreased to only about one millimeter. It will be found that a considerable quantity of liquid header-distillate collects in the receiving tank 3!, this distillate being characterized by very foul odor and a strong bluish phosphorescent cast. It

is characteristic of this header-distillate that if only an extremely minute quantity thereof is added to a good lubricating oil it will adversely affect the cast of the oil and render the oil unstable. This distillate collecting in receiver 3! while the gas oil out is being taken oil consists itself largely of light gas oil fractions containing a very large proportion of the total quantity of 7 0 the objectionable malodorous and unstabilizing constituents contained originally in the crude, the removal and separation of whichis one of the principal objects of the invention. The liquid caught in receiver 3!, therefore. comprises rela- 7 This crude 5 tively low-boiling constituents which escape condensatlon in the risers l6, header l1 and the ascending portions of header-distillate lines l8, l9, and are rapidly drawn off or sucked away from the heavier constituents which are condensed in that portion of the system and which flow thence through cooling coils l3, header l and run-down line 24 to the receiver tank 25. This separation of the lighter contaminating impurities from the desired liquid condensate is materially favored by the before-mentioned pressure differential which tends to cause flow through the deodorizer lines l8, l9, in preference to flow directly to the receiving tank 25 through the cooling coils and run-down line. This tendency of course affects not only the uncondensed vapors and gases in said lines [8, l9, but also to some extent the liquid condensate formed therein and in the risers I6. But in the case of said condensate this tendency is almost entirely overcome by the actionof gravity so that notwithstanding the slightly higher suction or vacuum in the headerdistillate lines, comparatively little liquid condensate is carried over as such through said lines provided the height of the overhead piping system l6, l1, I8, is properly adjusted and the lagging or heat insulation is also properly adjusted. This of course is governed to a large extent by the prevailing atmospheric temperature and varies with different seasons of the year. In practice, it is only necessary to have the piping system I6, I I, I 8, extend high enough from main vapor line l2, to ensure adequate condensation at the maximum seasonal temperatures to be encountered, and then to increase the amount of lagging as may be necessary to compensate for decrease of temperature in winter. When the system is operating, the risers l6, headers 11, and ascending portions of lines Ill, l9, should be quite hot, so that during the first part of the gas oil out sonsiderable gas-oil passes over into the header-distillate receiver 3|; and at all times these ascending lines should be so warm that the condensate formed therein is not cooled far below its condensing temperature. In this way the tendency formalddorous vapors and gases to be re-absorbed or dissolved by condensate flowing down the inner walls of the headers to the line I2 is minimized. It will therefore be seen that in the arrangement and mode of operation described, the hot still vapors and gases pass upwardly in countercurrent contact with downwardly flowing lubricating oil condensate, the hot condensate leaving the base of risers l6 relatively free from volatile contaminants.

It may be noted here that when the apparatus is functioning properly or to best advantage, a fog is distinctly discernible in the look-box 32 in line 30 leading to the receiver 3| while no fog is discernible in look-box 29 in the run-down line 24. This condition exists when the absolute pressure in the still l0, and deodorizer system, including header-distillate receiver 3 l is somewhat lower than the pressure in receiver 25, 26, or 21, whichever one of these receivers may be in use at the time, and such pressure difierential can readily be maintainedby properly setting the control valves in the connections to the vacuum pump so that the pump pull is wholly or mainly through the deodorizer system.

Thus far the discussion has dealt only with the initial or gas oil out. The distillation of gas oil continues until a test sample of condensate taken from run-down line 24 through sampling device 24l (similar to sampling device 33) shows a flash point which has been selected as proper to determine the conclusion of the gas oil cut. For example, this flash point may be selected as 290 F. in a typical instance. At this point the still temperature is ordinarily about 450 F. as 5 indicated by a pyrometer P having its thermocouple located about one inch above the bottom of the still. This marks thebeginning of the lubricating'distillate cut. In the meantime the operator has cracked or slightly'opened valve 42l controlling line 42 which connects receiver 26 with vacuum line 39, this being done before valve 26l is opened. In this way the pressure in receiver 26*can be reduced to that existing in receiver 25 at the end of the gas oil out, say'6 millimeters for example. This having been done, the operator now closes valve 42l, opens valve MI, and closes valve 25l, whereupon the stream of distillate flows into receiver 26. By this time it is no longer necessary to maintain as large a pressure differential as 4 or 5 millimeters because by far the greater part of the objectionable impurities have now been pulled over through the deodorizer system during the initial distillation which is intentionally forced somewhat, as by rapid firing, in order to bring about an immediate heavy rush of vapors through the deodorizer system, as described. Therefore after this initial rapid rush of vapors has been continued until a couple of hundred gallons of header distillate has collected in tank 3|, the system may then be operated with a much smaller pressure differential, say one millimeter or thereabouts. To this end the proper control valve 4| I, 42L or 43l, asthe case may be, may be opened very slightly, if necessary.

The cut collected in receiving tank '26 may, if

desired, be the entire quantity of lubricants that can be distilled from the particular crude undergoing treatment up to the temperature where substantial decomposition or cracking begins to take place in the still. However. it is usually more convenient to divide this lubricant yield into two or more portions or cuts, and in the present instance it will be assumed that the 45 lighter portion, corresponding to light and medium motor oil, is collected in receiving tank 26 and a heavier portion, corresponding to heavy motor oil, is collected in receiver 21. Thus, when the gas has been taken off as described and the succeeding lubricating distillate has been cut into tank 26, the distillation may be continued at an absolute pressure which has by this time been reduced usually to around 4 to 6 millimeters of mercury in the still and which may decrease gradually to as low as 1.5 to 3 millimeters toward the end of the distillation. After the gas oil has all been distilled 0135, it is found that the proportion of distillate that continues to come over through the deodorizer lines l8, I9 and. collect in receiver 3| is relatively very small indeed, quite commonly amounting to as little as one-half of one per cent by volume of the crude initially charged into the still for the entire remainder of the distilr lation, and being substantially less foulthan the header distillate obtained during the gas-oil cut. This later part of the header-distillate may therefore be collected separately and re-run if desired. On the other hand, the quantity of header-distillate obtained during the gas oil out amounts frequently to as muchas 5 per cent of the initial charge of crude. In this connection it must of course be borne in mind that this 5 per cent is largev gas oil which, in association deodorlzer lines because of the rapid rate of distillation and heavy pump pull on saidlines atthe beginning of the distillation, as above described. Until the still temperature as indicated by pyrometer P reaches about 630 F., the vac-' uum control valves are adjusted as may be necessary to maintain the before mentioned foggy appearance in the header-distillate line look-box 32, thus ensuring always a slightly lower pres-' sure in said line and in the still than in the particular receiver into. which the distillate stream may be flowing.

In a typical instance, the lubricating distillate is run into tank 26 until the flash point of a test sample is about 380 F., at which stage the still temperature approximates 550 F.; but it is to be understood that the selection of thepoint at which to cut the distillate into tank 21 may be varied as plant operating conditions require.

The lubricating oil.,distillate having been cut into receiver 21, the distillation continues as described with usually some further lowering of the absolute pressure, down to say 1.5 to 3 millimeters as observed in the still, which means a slightly higher pressure (e. g. 2.5 to 4 mm.) in receiver 21 as indicated by the manometer 21 The distillation is continued, running the lubricating cut into receiver 21' until tests of the distillate indicate that the point has been reached where decomposition or cracking is taking place or is about to take place in the still. The approach of this point is indicated whenthe flash point of successive test samples becomes stationary instead of gradually increasing as was the case during the earlier stages of the distillation. After remaining practically stationary for some time, the flash point of test samples will be found to be gradually lowering instead of increasing, and at this point it is best practice to cut the distillate into receiving tank 28. The

still temperature is now approximately 630 F4,

cedure which immediately causes a substantial increase in the size of the stream coming through line 24. Hardly any distillate other than normally fixed gases comes over through the deodorizer line from now on.

The distillation can be continued up to whatever maximum distillation temperature is found in practice to be commercially advantageous, notwithstanding the fact that the lubricating fraction thus collected in receiver 28 contains cracked products and is therefore not as high in grade as the oil collected in receivers 26 and 21.

The residueremaining in the still l0 after the distillation has been run as'described, is asphaltic in character and may be either a hard or soft asphalt, or a flux oil, depending upon the extent to which the distillation is carried. All of these products are valuable commercially, and the particular form in which it is desirable to obtain the residue in any given instance may to a considerable extent be determined by. market conditions existing at the time.

The gas oil fraction collected in receiver 25 may be considered to be a finished product and disposed of as such.

The lubricating oil cuts in receivers 26and 21 are good lubricating oil products but still contain a small proportion of organic acidswhich should be removed in order to render the products perfectly sweet, clean, and stable. Accordingly, these cuts are most desirablyre-run in a manner to be described presently.

The heavy lubricating distillate contained in receiver 28 also contains organic acids but in addition is further characterized by an appreciable content of cracked products resulting from decomposition of the oil in the still at tempera-J tures above about 630 F. This heavy lubricat-' ing cut is therefore also re-run to obtain finished products.

The re-running of the several cuts contained in receivers 26, 21 and 28 may be-conducted in the same manner in each instance if these cuts are re-run separately. It is not essential, however, that they be separately re-run, but on the contrary the entire yield of lubricants obtained neutralizing agent having the power to react with} the organic acids and with such other impurities as may be present in such manner as to enable substantially complete elimination and separation thereof from the oil in the re-run distillae tion. Various neutralizing agentsmay be employed for this purpose, but a caustic alkali, such as caustic soda, is effective and convenient to use and is therefore preferred. Examples of other basic reagents that may befemployed, however, are soda ash, lime, and the like. In using caustic soda as a neutralizing agent, this may be employed in a .water solution of say30 to-40"- Baum strength. Assuming a 40 Baum solution, it is found s'uflicient to employ about a pint of the solution for each barrel of lubricating oil distillate to be re-run. The exact amount may vary somewhat depending upon the nature of the starting material. Such a proportion of the solution having been added to thecharge ofoil, the charge is then thoroughly agitated, as by blowing in air, or otherwise,'until the neutralizing agent has been uniformly distributed through the charge. The charge is then re-run in apparatus which may be of exactly the same character as that shown inFigs. 1 and 2 and hereinabove described in detail. The re-run distillation may-be carried out in precisely the same manner as the first distillation except that the particular cuts of lubricating oils made may be different from or more 'numerous than those of the first distillation, it being convenient ordinarily to so determine the cuts as to obtain a. range of finished oils corresponding generally to commercial types of oils demanded by the trade.

In thus re-running the lubricating oil distillate initially collected in receiver 26, a certain further quantity of non-viscous distillate is obtained of which the viscosity ranges from 60 to seconds at F., but the proportion is relatively very small. A somewhat larger amount, approximating say 10 per cent, is also obtained in re-running the heavy cracked lubricating dis-'- tillate initially collected in receiver 28. JIhe residues remaining after re-running the distillates initially collected in receivers 26, 21 and 28 are accumulated, and when the accumulation is suflicient it is also re-run in the manner already described and approximately 90 per cent of the accumulation is recovered as valuable lubricants. The final residue from such re-run of accumulated residues may be 'disposed of as fuel oil or otherwise as may be desired.

U. S. Govemment- Standard Specification 2C (Technical Paper 323A, Department of the Interior, 1924).

' Gas 100 200 300 500 750 1 000 1,300 Product oil pale pale pale pale pale pale pale Percent of crude 24. 23 o. 70 a 38 5. 65 4.19 5. 65 5. 41 2.16 Gravity(B.). 29. 22. 0 20. 7 20. 2 19. 9 19. 3 18. 9 l8. 7 Flash F.)-- 335 375 385 415 435 460 480 Fire F.) 390 445 450 500 530 565 590 Viscosity at 100 F 105 221 310 508 740 137g 1258 Color N.P.A-. 1. 75 2. 0 2. 25 2. 5 3. 0 26 t2 5 Coldtest( F.) -35 -20 -5 'o '5 "5 C 0 hr a d s o n carbon residue value- 01 .02 .03 .04 .07 09 l0 Demulsibility at 130 1620 1620 1620 1580 1500 1500 1200 R. E. test 1 1 2 2+ 3 6 7 1 Resistance of an oil to emulsification, as specified by A. S. T. M

Recapitulation-Total yield Per cent Gas oil 24. 23 Finished lubricating oil 41. 14 Fuel oil 0. 64 Asphalt. 33. 68

The oils of which identifying data are given in the foregoing table are typical of novel lubricating oils that can be produced by the process of the invention. They are all narrow-cut lubricating oils, that is, oils characterized by narrow viscosity range and narrow boiling point range, and obtained by overhead distillation, all as set forth in this applicant's prior Patent No. 1,448,709 aforesaid, but they are'sharply distinguishable from the oils disclosed in said prior patent by the fact that, for any given viscosity, the flash and fire points are, respectively, at least about 10 F. higher'and, in the case of the higher seconds at 100 F. as measured on the Saybolt universal viscosimeter. While the general color classification of this 200 viscosity product is given in the table as pale, an oil having an. N. P. A.

color of 2.0 would actually be designated in the present custom of the trade as a Filtered pale oil, and in fact this trade designation would apply to all oils having an N. P. A. color not greater than 4.5. However, as it is not necessary to filter oils produced by the present process to attain such high grade color, they are referred to 5 in the above table merely as pale in order not to convey the impression that they have beenfiltered.

The series of lubricating oils whose identifying characteristics and properties are set out in \0 the above table are new products in the art and are. clearly distinguishable from lubricating oils heretofore known. Moreover, the particular series of oils above given is merely typical of novel lubricating oils that call be manufactured 15 in accordance with the invention. The N. P. A. color, the cold test, and the Conradson carbon residue percentage, characterizing the new oils, are in each instance closely similar to the corresponding identifying characteristics of the lubrieating oils produced in accordance with the process disclosed in the Schulze Patent 1,448,709-ber fore mentioned. However, the present oils are distinguishable from the oils disclosed in the aforesaid Schulze patent by the fact that the flash and fire points are invariably considerably higher, always at least 5 F. higher, and ordinarily from 10 to 40 higher.- This superiority in fiash and fire points is the more marked the higher is the viscosity of the oils compared.

While the dimensions of the various parts of the apparatus system herein disclosed may of course be varied widely in practice within the scope of the invention, the dimensions and capacities of the more important'parts of one form tal cylindrical still 10 is nine feet in diameter 40 and thirty feet long, giving an approximate charging capacity ofabout 250 barrels of 42 gallons each. Each of the ten offtake lines l2 has an internal diameter of ten inches, and the vertical portion I2 thereof rises to a height of 45 about eighteen inches above the still, it being desirable to have this height as small as conveniently possible. Each of the cooling coils l3, into which the oiftakes l2 discharge liquid, is a three-inch pipe; and the header 15 intowhich the ten cooling coils l3 discharge is ten inches in diameter, as is also the run-down line 24 leading to the horizontal cylindrical receivers 25, 26, 21 and 28, each of which latter is in this instance seven feet in diameter by sixteen feet long.

Each of the ten risers I6 is six inches in diameter, and extends upward ten feet to enter the header II, which is eight inches in diameter. The five deodorizer lines I 8, l9, are of four-inch pipe and extend ten feet higher. The cooling coils 20, 2|, into which the lines l8, l9, discharge, are six-inch pipes; and the header 22 is ten inches in diameter as is also the line 30 leading therefrom to the small receiver 3| which is four feet in diameter and sixteen feet long. Them; vacuum line 39, 40, is ten inches in diameter .as is also the pipe 44-leading therefrom to rundown tank 28. The pipes 4|, 42 and 43 connecting tanks 25, 26 and 21 to vacuum line 39 are four inches in diameter; while the pipes 25, 26 21 and 28, which connect said tanks with rundown line 24 are six inches in diameter.

In general, it is important that the piping connections, both vapor and liquid-lines, between the still and the vacuum-producing means. shall 76 be of such ample capacity as to favor free and substantially unobstructed pull of the vacuumproducing means upon the still at all stages and under all conditions of normal operation. It is also inipc-tant that the vacuum-producing means be able at all times to exert a direct and free pull through the cooling coils and associated piping upon the receiving tanks; but it is also desirable that the arrangement shall be such that the pull of the vacuum-producing means upon the still can be maintained slightly greater than the pull of said means upon the receivers, thus creating a pronounced tendency for the distillate from the still to flow toward the vacuum pump by way of risers and overhead lines Iii-l8 as already described and for the purposes set forth. This object can be achieved in various different ways, but in the specific arrangement and design of the apparatus herein disclosed it is achieved at least in part by reason of the fact that in pulling upon the receiving tanks 25-28, the action of the vacuum-producing means is to some extent afiected by the liquid in the cooling coils l3 which, although by no means filling said coils in normal operation, probably exerts a slight throttling action.

The process of the invention may alsobe carried out with the aid of steam, and in some classes of work the employment of steam as an auxiliary distilling agent is of advantage. Fig. 3 illustrates how the apparatus system may be arranged where the distillation is to be carried on with the aid of steam, most desirably superheated, introduced into the charge through valved pipe S. In this arrangement, the overhead vapor lines l8 lead to a cold condenser indicated generally at l4, there being most desirably a separate condenser coil 20 for each of the lines l8. The water in condenser tank l4 should be maintained substantially cooler than that in tank Id. In the coils 20', both steam and oil vapors condense and are then discharged into header 22',from which the liquid productsare conveyed by line 30" to a receiver 3|. While only one receiver 3| is here shown, it is sometimes desirable in practice to employ two'such receivers into which the liquid products may be directed alternately in order that the condensate may be more readily removed from time to time without disturbing operation of the system as a whole. It is also sometimes desirable to operate with-two or more such receivers 3! in series. Whether one or more of these tanks 3| be employed, it or they should be kept cold, but not below the freezing point of water, by suitable cooling means such, for example, as cooling coils C through which a cooling medium of any suitable character may be continuously passed.

From thereceiver or receivers 3|, the vacuum line 39, M, extends to the vacuum pump 31 as before described, the system as a whole being similar, except in the particulars above noted, to that illustrated in Figs. 1 and 2.

In the specific example hereinabove given, illustrating how the method of the invention may be practiced with the aid of the apparatus shown in Fig. 1, the manufacturing procedure involves two distillations, namely, a first distillation of a crude without the addition thereto of a neutralizing agent but with separation of a large proportion of the malodorous and other impurities as described; and a second or re-run distillation of the lubricating distillate or distillates in the same manner but with the addition of a neutralizing agent, such as caustic alkali, to the oil that is to be so re-run. However, it is not to be inferred that the invention is restricted to a procedure involving two or more .successive distillations. On the contrary it is feasible and in some cases advantageous to add a neutralizing agentdirectly in the first instance to the crude or residuum used as a starting material and to distill over finished lubricating oil products directly without the necessity of re-running. However, where the crude or residuum employed as starting material is an asphaltic base material, it is ordinarily desirable not to add a neutralizing agent directly thereto because this would decrease the value for many purposes of the asphalt residue left in the still at the end of the distillation. By using a two-stage procedure of the character hereinabove described, this difficulty is avoided. an asphaltic residue free from alkali being obtained from thefirst distillation, while the presence of alkali in the final residuum resulting from the last of the re-run distillations is not objectionable since this residuum is not asphaltic and is useful only as a fuel oil. Where the crude or residuum employed as starting materialis nonasphaltic in character and yields a distillation residue in which the presence of alkali is unobjectionable, or where it is feasible commerciallyto dispose of an 'asphaltic residuum containing. alkaline matter, the foregoing considerations are not so important, and it is therefore practicable so in some cases to manufacture finished products direct by a single distillation from the crude starting material.

Nor is it to be inferred from the specific description hereinabove given that the process of the invention is restricted to batch or intermittent distillation. A method involving batch distillation has been described hereinabove merely for purposes of illustration and it is entirely feasible to practice the new process in a con- 40 tinuous manner, employing a battery of stills through which the oil passes successively, each still yielding a distillatehaving characteristics determined by the conditions under which that still is being operated.

Where the starting material is a crude oil containing a' rather large proportion of gas oil, say 25 to 30 per cent, such as Smackover crude for example, or where the crude contains a considerable proportion of other relatively light fractions such as gasoline, naphtha and kerosene, it is feasible to top the crude in an ordinary pipe still or steam still down to a point where the residue has an initial boiling point of around 300 to 350 F. at 5 to 10 millimeters absolute pressure. This of course involves the use of temperatures in the topping plant of 575 to 600 F. or thereabouts, operating underv atmospheric pressure.

The process of the invention is also applicable to the treatment of parafllne base crudes and residua, but in treating such starting materials it is necessary to guard againstclogging of the vapor lines, cooling coils, etc. with" congealed wax. This can be readily done as by steamjacketing the apparatus parts in question and also maintaining the receiving tanks warm so that the condensates collecting therein can be removed and suitably treated for separation of contained wax by centrifuging or other appropriate method.

In practicing the process, conducting the distillation, whether in 'one stage or more than one stage, under strictly non-oxidizing conditions is a matter of vital importance for attainment of satisfactory results. Every precaution gs should be taken to ensure absolute tightness of the apparatus by welding all joints and seams as already stated. Continual leakage of even a relatively very minute quantity of air into the system can seriously afiect the proper operation of the process and result in production of inferior products. It is also important to avoid as far as possible refluxing of distillate to the still since this results in discoloration and other damage to the lubricating products by cracking or otherwise I prior to attaining still temperatures around 630 F.

It is feasible to use other types of oil-Vaporizers than the horizontal cylindrical still type herein disclosed by way of illustration. Thus, for example, pipe stills'operating in conjunction with appropriate dephlegmators or separating drums of construction suitable to withstand the use of extremely low absolute pressures, can be used to advantage in some cases.

It is found in practice that in the described rerunning or redistillation of the lubricants obtained in the first distillation after the gas oil has been taken off and before cracking temperatures have been reached (i. e. the lubricants initially collected in receivers 26 and 21, in the specificillustrative example above given), those of the resultant finished lubricating oils that have'a viscosity of 300 seconds Saybolt (at 100 F.) and higher are tasteless as well as odorless. Notwithstanding the fact that they are direct distillates, not treated with acid or filtered, they are as tastelessv and odorless as the best grades of so-called white medicinal oils now on'the market. Nevertheless they show color as indicated in the table hreinabove given. Heretofore no tasteless mineral oils have been known that were not water-white in color, and invariably they have been acid-treated and upon redistillation, whether at ordinary pressures or very low absolute pressures, they yield decomposition products. Tasteless mineral oils having appreciable color are novel products in the art.

The process of the invention may also be employed for production of finished lubricating oils from partially finished lubricating oils made by other processes. Furthermore even finished lubricating oils resulting from such other processes may be re-distilled in accordance with theprinciples of this invention to produce lubricating oils of much higher grade. The use as starting material in the present process of such finished or partially finished oils produced by other processes is an important practical phase of the present invention.

It is to be especially noted that the present invention makes possible the manufacture of good finished lubricating oils as direct overheaddistillates from any crude, residuum, or other heavy mineral oil material, no matter how high may be its content of sulfur, organic acids or other contaminating impurities, and that no acid treatment, filtration, or other additional finishing treatment is required to produce high grade lubricants of the best color, greatest stability and other desirable characteristics.

What I claim is:

1. The process of producing lubricating oil distillates which comprises mixing a basic neutralizing agent with a body of mineral oil containing lubricating oil components and also lighter-and lower-boiling odor-producing components; heating said body of mineral oil to vaporizing temperature and thereby obtaining lubricating oil vapors in mixture with malodorous gases and relatively light condensable vapors, conducting the resultant hot vapors and gases into a zone wherein they are caused to pass upwardly in countercurrent contact with downwardly flowing lubricating oil condensate formed. at a higher point in said zone,

so regulating the temperature conditions in said zone as to ensure suflicient cooling of the vapor to condense therefrom substantially all the desired lubricating components thereof but, at the same time, to avoid further cooling to a temperature so much below the vaporizing point of said condensate as to permit condensation of said relatively light malodorous vapors or substantial absorption of said malodorous vapors and gases by said condensate, rapidly conducting the uncondensed vapors and gases away from said zone, separately conducting the hot lubricating oil condensate. away from said zone and out of contact with said uncondensed vapors and gases, and then, after the condensate has left said zone, permitting it to cool further, all the stated operations being conducted under non-oxidizing conditions and under low absolute pressure. 2. In the manufacture of useful mineral lubricating oil products from mineral oil containing difiicultly separable but relatively low-boiling impurities, the process which comprises distilling a mineral oil in the presence of a basic neutralizing agent under an absolute pressure not exceeding 25 millimeters of mercury and under non-oxidizing conditions, conducting the distillation vapors upward and cooling the same under such pressure to a temperature not substantially below the vaporizing point of relatively heavy lubricating components thereof at such pressure while rapidly withdrawing uncondensed lighter vapors, and 85 still further cooling the resultant.condensate out of contact with said uncondensed vapors 3. In the manufacture of lubricating oils, the process which comprises mixing a small proportion of a basic reagent with mineral oil compris- 4i ing lubricants associated with relatively light impurities, distilling said oil under an absolute pressure notexceeding about 25 millimeters of mercury and under non-oxidizing conditions to obtain mixed vapors therefrom while avoiding substantial refluxing to the body of mineral oil being distilled, conducting the mixed vapors rapidly into a cooling zone also maintained at an absolute pressure not exceeding about 25 millimeters of mercury and at a temperature sufiiciently low to produce a lubricating oil condensate but not much lower than the condensing temperature, whereby to prevent extensive condensation of said relatively light impurities or absorption thereof by said condensate and separately conducting uncondensed impurities and said lubricating oil condensate away from said zone under suction, the suction being maintained higher ,upon said impurities than upon said condensate.

4. The process as set forth in claim 3, further 60 characterized by the fact that the pressure at which the lubricating fractions are distilled and condensed does not exceed 15 millimeters absolute.

5. The process as set forth in claim 3, further 65 characterized by the fact that the pressure at which the heaviest lubricating fractions are distilled and condensed does not substantially exceed 5 millimeters.

6. In the manufacture of lubricating oils from 7 mineral oil material containing lubricating constituents together with associated impurities of lower vaporizing point that are largely inseparable therefrom by usual distillation methods and that undesirably affect the odor, color and sta- 1' and at an absolute pressure not exceeding 25 millimeters of mercury, in the presence of an added basic neutralizing agent, conducting the resultant distillation vapors and gases into a zone, maintained under absolute pressure not exceeding 25 millimeters of mercury, wherein they are caused to pass upwardly in countercurrent contact with downwardly flowing lubricating oil condensate formed at a higher point in said zone, so regulating the temperature conditions in said zone as to ensure suiflcient cooling of the vapor mixture to condense therefrom substantially all the desired lubricating oil components thereof but, at the same time, to avoid further cooling to a temperature so much below the vaporizing point of said condensate as to permit condensation of vaporous impurities or substantial absorption of either vaporous or gaseous impurities by said condensate, sucking away uncondensed vapors and gases out of contact with the hot lubricating condensate under an absolute pressure at least as low as that at which vaporization was effected in the distillation, and separately conducting away from said zone and cooling said lubricating condensate.

7. In the manufacture of lubricating oils, the process set forth in claim 6, further characterized by the fact that the pressure under which vaporization and condensation of the relatively heavy lubricating fractions is effected at no time exceeds 10 millimeters of mercury absolute and does not substantially exceed 5 millimeters absolute during a substantial part of the distillation.

8. In the manufacture of lubricating oils, the process set forth in claim 6, further characterized by the fact that the pressure under which vaporization and condensation of the relatively heavy lubricating fractions is effected at no time exceeds 10 millimeters of mercury absolute and does not substantially exceed 5 millimeters absolute dur-' ing a substantial part of the distillation, and by the fact that the difference between the absolute pressures under which the uncondensed vapors and the condensate are respectively conducted away is of the order of magnitude of a few millimeters of mercury.

9. In the manufacture of lubricating oils from mineral oil material containing lubricating constituents together with associated impurities of lower vaporizing point that are largely inseparable therefrom by usual distillation methods and that undesirably affect the odor, color and stability of finished lubricating oils containing the same, the process which comprises adding a basic neutralizing agent to such mineral oil material and vaporizing lubricating fractions therefrom in a still under strictly non-oxidizing conditions and under absolute pressure not exceeding 15 millimeters of mercury, while avoiding substantial refluxing of condensate to the still, rapidly conducting away resultant distillation vapors and gases, without substantial cooling, to a point beyond where refluxing to the still can occur, then cooling said vapors sufficiently to condense the greater part of the lubricating constituents thereof while avoiding cooling substantially further than is necessary to effect this result, and sucking away uncondensed vapors and gases out of contact with the hot lubricating condensate under an absolute pressure at least as low as that at which vaporization was effected in the distillation, and separately conducting away and cooling said lubricating condensate under a somewhat higher absolute pressure.

10. In the manufacture of lubricating oils from mineral oil material containing lubricating constituents together with associated impurities of lower vaporizing point that are largely inseparable therefrom by usual distillation-methods and that undesirably affect the odor, color and stability of finished lubricating oil containing the same, 'the process which comprises vaporizing lubricating fractions from such mineral oil material in a still under strictly non-oxidizing conditions and at an absolute pressure not exceeding 25-millimeters of mercury while avoiding substantial refluxing of condensate to the still, rapidly conducting away resultant distillation vapors and gases, without substantial cooling, to a point beyond where refluxing to the still can occur, then cooling said vapors sufliciently to condense the greater part of the lubricating constituents thereof while avoiding cooling substantially further than is necessary to effect this result, sucking condensate and uncondensed vapors and gases away from each other through separate conduit systems, the suction applied tcrsaid uncondensed vapors and gases being greater than that applied to said condensate, and further cooling said uncondensed vapors and gases to obtain therefrom a lower boiling condensate, the process further including the addition of a basic neutralizing agent to the mineral oil material from which the lubricating constituents are to be vaporized.

11. In the manufacture of lubricating oils, the process set forth in claim 6, further characterized by the fact that the pressure under which vaporization of the lubricating fractions is effected at no time exceeds 10 millimeters of mercury abso lute and does not substantially exceed 5 millimeters absolute during a substantial part, of the distillation, and by the fact that the difference between the absolute pressures under which the uncondensed vapors and the condensate are respectively conducted away is of the crder'of magnitude ofa. few millimeters of mercury.

12. In the manufacture of lubricating oils from mineral oil material containing lubricating constituents together with associated impurities of lower vaporizing point that are largely inseparable therefrom by usual distillation methods and that undesirably affect the odor, color and stability of finished lubricating oils containing the same, the process which comprises adding a basic neutralizing agent to such mineral oil' material and vaporizing lubricating fractions therefrom in a still under strictly non-oxidizing" conditions and at an absolute pressure not exceeding 10 millimeters of mercury and not substantially exceeding 5 millimeters during a substantialpart of the distillation, while avoiding substantial refluxing of condensate to the still, rapidly conducting away resultant distillation vapors and gases, without substantial cooling, to a point beyond where refluxing to the still can occur, then cooling said vapors sufl'iciently to condense the greater part of the lubricating constituents thereof while avoiding cooling substantially further than is necessary to effect this result, sucking condensate and uncondensed vapors and gases away from each other through separate conduit systems, the suction applied to said uncondensed vapors and gases being greater than that applied to said condensate, and further cooling said uncondensed vapors and gases to obtain therefrom a lower boiling condensate.

13. In the manufacture of lubricating oils, the process as set forth in claim 12, further characterized by the fact that the difference in pressure under which the uncondensed vapors and the condensate are respectively conducted away is of the order of magnitude of a few millimeters of mercury.

14. In the manufacture of lubricating oils, the process which comprises distilling lubricating fractions from a crude oil or residuum at absolute pressures not exceeding 25 millimeters of mercury, and below 10 millimeters for the major part of the distillation, and, redistilling the resultant lubricating oil in the presence of a basic neutralizing agent at absolute pressures of similar magnitude.

15. In the manufacture of lubricating oils, the process set forth in claim 14, further characterized by the fact that the crude oil or residuum employed has an asphaltic base and contains difficultly separable relatively low boiling contaminants injurious to finished lubricating oil.

16. In the manufacture of lubricating oils, the process of improving previously manufactured lubricating oils which comprises subjecting such a manufactured lubricating oil to distillation in the presence of a basic neutralizing agent at absolute pressures not exceeding 25 millimeters of mercury and most desirably substantially below 10 millimeters, and collecting directly a lubricating oil distillate of better stability than such previously manufactured oil.

17. The process of manufacturing high-grade finished lubricating oils without acid treatment or filtration which comprises vaporizing, under absolute pressure not exceeding 25 millimeters of mercury and under non-oxidizing conditions, a lubricant-containing mineral oil crude or residuum high in combined sulphur, nitrogen, organic acids, or complexes including some or all of such constituents, thereby producing lubricating oil vapors mixed with vaporous and gaseous malodorous impurities which are lower-boiling than the lubricating oil components, lowering the temperature of the mixture sufficiently to condense most of the lubricating oil components therefrom, then separately and rapidly conducting away out of contact with each other the resultant lubricating oil condensate and the uncondensed vapors and gases, said lubricating condensate being maintained under an absolute pressure not substantially exceeding 10 millimeters of mercury while flowing out of contact with the aforesaid uncondensed vapors and gases, and further cooling and collecting said condensate, under like low absolute pressure as a high grade finished lubricating oil requiring no acid treatment or filtration to render it fit for immediate use.

18. In the manufacture of lubricating oils from mineral oil materials containing, or yielding upon distillation, relatively volatile malodorous constituents difficultly separable from a desired lubricating oil product, the process which comprises heating such mineral oil material and obtaining therefrom lubricating oil vapors'in association with relatively volatile malodorous. constituents, leading such mixture of vapors and gases away through a plurality of large-diameter conduits arranged in multiple, cooling the mixture sufficiently to obtain therefrom a lubricating oil condensate while rapidly sucking away gases and uncondensed vapors. causing the condensate to fiow, still warm but out of contact with said gases and uncondensed vapors, in a plurality of streams through large-diameter conduits arranged in multiple, and applying to said condensate while so flowing a highyacuum corresponding to an absolute pressure of between 1.5 and 25 millimeters of mercury.

19. The process of manufacturing lubricating 5,

oils as overhead distillates which comprises distilling mineral oil which contains lubricating oil components in association with odor-producing components in the presence of a basic neutralizing agent under absolute pressure not exceeding 1 25 millimeters of mercury and under non-oxidizing conditions, thereby producing a mixture of lubricating oil vapors with difficultly separable vaporous and gaseous lower-boiling malodorous contaminants, conducting the mixed distillation 15 vapors upwardly while cooling the same under such pressure sufficiently to condense desired lubricating oil components therefrom while avoiding cooling to the condensing point of the associated lower-boiling malodorous contaminants and rap- 2 idly withdrawing uncondensed vapors and gases out of contact with the resultant lubricating oil condensate, then still further cooling said condensate under such pressure out of contact with said uncondensed vapors and gases. 25

20. The process as claimed in claim 19, wherein the stated operations are all effected under an absolute pressure not exceeding 15 millimeters.

21. The process as claimed in claim 19, wherein the stated operations are all effected under an 30 absolute pressure which does not exceed 15' millimeters andis for the most part below 10 millimeters.

22. The process of manufacturing high-grade finished lubricating oils without acid treatment 35 or filtration, which comprises vaporizing, under absolute pressure not exceeding 25 millimeters of mercury and under non-oxidizing conditions, a lubricant-containing mineral oil crude or residuum high in combined sulphur, nitrogen, organic 4o acids, or complexes including some or all of such constituents, thereby producing lubricating oil vapors mixed with vaporous and gaseous malodorous impurities which are lower-boiling than the lubricating oil components, subjecting such 5 mixed vapors in a traveling stream to reflux condensation under absolute pressure not exceeding 25 millimeters and at a temperature above the condensing temperature of said impurities but sufiiciently low to condense lubricating oil components, rapidly sucking away uncondensed vapors and gases, and flowing the resultant lubricating oil condensate out of contact with said traveling stream of mixed vapors while'cooling said condensate still under absolute pressure not exceeding 25 millimeters, and collecting the same as a high grade finished lubricating oil requiring no acid treatment or filtration to render it fit for immediate use.

23. The process as claimed in claim 22, wherein the stated operations are all effected under an absolute pressure not exceeding 15 millimeters.

24. The process as claimed in claim 22, wherein the stated operations are all effected under an 6.3 absolute pressure which does not exceed 1. millimeters and is for the most part below 10 millimeters.

25. The process of manufacturing lubricating oils as overhead distillates which comprises distilling mineral oil which contains lubricating oil components in association with odor-producing components in the presence of a basic neutralizing agent under absolute pressure not exceeding 25 millimeters of mercury and under non-oxidizing conditions, thereby producing a mixture of lubricating oil vapors with difficult-1y separable vaporous and gaseous lower-boiling malodorous contaminants, conducting said mixture into a condensing zone and cooling the mixture under such pressure sufiiciently to condense desired lubricating components therefrom while rapidly withdrawing uncondensed vapors and gases from said zone, separately conducting the resultant lubricating condensate away from said condensing zone and further cooling the same under such pressure and out of contact with said uncondensed vapors and gases.

26. The process as claimed in claim 25,- wherein a small proportion of caustic soda is employed as the neutralizing agent, and the stated operations are all effected under an absolute pressure which does not substantially exceed 15 millimeters and is for the most part below 10 millimeters.

JOHN E. SCHULZE. 10 

